PIIASMID.E. 



fi7 



Division II. PTEROPHASMINA. 



Pteropliasmiiia, G. R. Gray, Si/n. Phosm. p. 21. 

 Piiasmata subaptera, P. tlejiressa, et P. alata, Licht. 



Pursuing the principle laid down in the introductory 

 observations of this work, we have now arrived at those 

 groups which in their imago state acquire more or less per- 

 fectly developed organs of flight, either in both sexes or in 

 the males, the females being in the latter case either en- 

 tirely destitute of even rudimentary wings and wing-covers, 

 or having them very small. In all cases, however, except 

 indeed in the females of the singular genus Phyllium, the 

 tegmina are of small size, and incapable of forming a 

 defence to the wings ; to supply which want, a provision 

 is made in the anterior area of the hind wings being of a 

 more coriaceous nature than the hinder portion, the former 

 being moreover longitudinally veined, whilst in the posterior 

 area the veins are arranged like the ribs of a fan ; so that 

 this portion of the vring alone folds up, and is then covered 

 by the flattened costal area. In Phijlliiim, however, by a 

 singular modification, the wing-covers of the females, when 

 shut, are so large that they nearly cover the abdomen, — a 

 beautiful adaptation indeed, since the delicate texture of the 

 dorsal membrane of the hind part of the broad and flattened 

 body, as well as the large mass of eggs which it contains, 

 require more defence than could have been afforded either 

 by abbrenated tegmina, or wings even of large size folded 

 up in the ordinary manner. Hence, as well as from the 

 sluggish habits of these insects, the inutility of a pair of 

 membranous wings ; and we accordingly find them reduced 

 to mere rudiments (except in one species described by De 

 Haan). The males, on the other hand, have the true 

 wings of large size and very delicate in structure, with the 

 costal area itself quite membranous ; but yet the tegmina, 

 preserving the true family character, are only of small size, 

 and useless as means of defence to the wings. 



Some difficulty will doubtless be experienced in respect 

 to specimens of winged species not yet arrived at maturity, 

 in which the wings and wing-covers only a])pear in a very 

 rudimental state, as contrasted with others in which these 

 organs, in the final state, are also merely rudimentary. I 

 believe, however, that a careful examination of their struc- 

 ture will sufficiently exhibit the difference between these 

 organs in the two different conditions of existence. In 

 Plate XXVII. fig. 4, I have represented the pupa of a 

 winged species, in which the rudimental wings extend as 

 far back as the hind margin of the metanotum : they are, 

 however, not free in their movement, and quite different 

 in texture from the wings of, for instance, the species 



Phasmodea, sect. 2 et 3, Bitrm. Ilandh. d. Ent. o. c. 

 Phasma, sect. 1 et 2, De Ilnnn, o. c. 10". 



figured in the following Plate (XXVIII. fig. 4), or the 

 female represented in Plate XI. fig. 2, The condition of 

 the organs of flight in the immature states of the genus 

 Phyllium is represented in Plate XXXI. 



Another difficulty results from our imperfect knowledge 

 of the opjiosite sexes in so great a proportion of the species 

 described in this work. The great diversity in the sexes 

 of many of the insects described by the earlier writers upon 

 the family, led them not only to consider the males as 

 distinct species from the females, but also as belonging to 

 different genera placed in different sections of the family. 

 Wherever it has been possible, this difficulty has been cleared 

 up in the present work : but there are many male insects 

 described in the following pages, especially in the genera 

 Necroscia and Phasma, which in all probability possess 

 wingless partners ; whilst it is equally probable that manv 

 of the wingless female insects already described in the pre- 

 ceding pages, especially in the genus Bacteria, may prove 

 to possess winged males. The study of such species as 

 Mo7iandroptera inuncans, and the remarkable insect which 

 I have described under the name of Prostasis, is especially 

 instructive — showing, in the latter case, that a female 

 insect, which may be completely mistaken for a female Ba- 

 cillus, possesses a winged male. The classification of the 

 species can only therefore, at present, be regarded as ap- 

 proximate ; nor will it be perfected until we are acquainted 

 with a far greater number of the true pairs of the species 

 than we are able at present to determine. 



Following the order suggested by the amount of alary 

 development, the following arrangement commences with 

 those groups in which the wing-covers and wings are deve- 

 loped in the slightest degree, and terminates with those in 

 which they are of large size, and fitted for flight in both 

 sexes. A character connected with the organs of flight, of 

 some importance, but which has not hitherto received so 

 much attention as it deserves, and which must be given to 

 it when the knowledge of the sexes of the different species 

 is more extended, exists in the furcation or simplicity of 

 the main vein of the costal area of the wings ; the furcate 

 character occurring occasionally in both sexes, and some- 

 times only in the females. 



Considerably greater imjiortance has been given to the 

 possession or absence of ocelli, as affording sectional divisions 

 in the family, than I am disposed to concede to this pecu- 

 liarity; these organs being sometimes scarcely capable of 



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